Zigzag sewing mechanism of doublethread sewing machine



ZIGZAG SEWING MECHANISM OF DOUBLE-THREAD SEWING MACHINE Filed April 2,1951 HIDENORI $5.356

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ZIC-ZAG SEWING MECHANISM OF DOUBLE-THREAD SEWING MACHINE Filed April 2,1951 4 Sheets-Sheet s jump NM" aka 5,, E954 HiDENORl sumo ZIGZAG SEWINGMECHANISM OF DOUBLE-THREAD SEWING MACHINE Filed pril 2. 1951 4Sheets-Sheet 4 Patented Oct. 5, 1954 UNITED STATES PATENT OFFICE ZIGZAGSEWING MECHANISM OF DOUBLE- THREAD SEWING MACHINE Hidenori Sudo, Osaka,Japan Application April 2, 1951, Serial No. 218,788

Claims priority, application Japan April 4, 1950 2 Claims. 1

This invention relates to mechanism by which, in addition to theordinary vertical motion of the needle-bar and the rotating motion ofthe shuttle of the ordinary straightly advancing sewing mechanism, theneedle-bar is made to shift in left and right directions in the amountof the zigzag, at around the upper limit of the vertical movement of theneedle-bar, for the purpose of performing zigzag sewing. At the sametime the shuttle also is started to swing in the direction of the shiftand in the same amount as the shift of the needle-bar. The shuttle ismade to shift at will within the limit of the amount of zigzag. All thisis done by manipulation of a lever. The

invention relates also to the construction of such mechanism. Its objectis the provision of mechanism to be used for various types of appliedsewing which combine straight-running sewing width with zigzag Width.

Fig. 1 is a front view in vertical longitudinal section of a sewingmachine embodying my invention.

Fig. 2 is a plan view of some of the operating mechanism of the machineof Fig. 1.

Figs. 3 and 4 are, respectively, views from the bottom and from thefront of the machine showing the principal parts of the zigzag stitchshifting mechanism.

Figs. 5 and 6 are, respectively, end elevations of the parts of Fig. 3as seen from the left of that figure on the line a--a and from the rightof that figure on the line b-b.

Fig. '7 is a series of four diagrams illustrating how the basic seams ofzigzag sewing are obtained by my mechanism.

Fig. 8 is a series of perspective views coordinating the sewingmovements of Fig. 7 with the mechanism of the other figures.

The zigzag sewing mechanism of the double thread sewing machine (lockstitch machine) to which this invention relates, is a novel mechanism inwhich, as above mentioned, the needle-bar is made to shift in left andright directions only in the amount of the zigzag, at around the upperlimit of the needle-bar movement, for the purpose of performing zigzagsewing. At the same time the shuttle also is swung in the direction ofthe shift in the same amount as the shift of the needle-bar, and made toshift at will within the limit of the zigzag by manipulation of a shiftlever. All this is in addition to the ordinary vertical movement ofneedle-bar and the rotating movement of shuttle of the ordinarystraightly advancing sewing mechanism.

An example of the actual construction of the mechanism is given below.

Referring to the drawings, the triangular cam 28, which rotates at areduced speed of one half through the speed-reduction gears 46, 41 fromthe main shaft I, is made to slide in a groove in the forked connectingrod 29. This rod is pivoted to the pivot in the lower end ofthe'arm-handle 43 fitted on the basic shaft 3| to which is also affixedthe shift lever 32. At the same time the arc groove .33 which isprovided at the back of the forked connecting rod 29 is used to guidethe slider 36. The slider is supported on one end of a connecting rod 34by an axial pin 35. The other end of the connecting rod is linked to thearm 25 which in turn is carried by the rock shaft 9 of the shuttle l9and the needle bar 4. Movably carried on the rock shaft 9 is a sleeve 45for the zigzag shift lever 31. This sleeve 45 has an arm plate 38 lyingparallel to the connecting rod 33. The end of the arm plate 38 isconnected with the center of the connecting rod 34 by means of theconnecting piece 4|. The distance between the said connection 48 on theconnecting rod 36 and the connection 24 on the arm rod 25 fixed to theoscillating rock shaft 9, and the distance between the two ends 39 and 9of thearm plate 38 are made equal in length. It is so constructed that,when the shift lever 32 is placed at central position and the center ofthe slider 35 of the connecting rod 34 moving in the arc groove 33 onthe back side of the forked connecting rod 29 is made to agree with thepivot 30 of the forked connecting rod 29, the four following distances,namely, the distance between the said fixed pivot 30 and the basic shaft3| of the shift lever 32, the distance between the said pivot 38 and therotating shaft 42 of the triangular cam 28, the distance between theupper end 39 and the lower end 40 of the connecting piece 4 l, and thedistance between the rock shaft 9 and the connection 24 of the arm rod25 fastened to the oscillating rock shaft 9 are equal in length andparallel each other. Under these conditions of equality it is also truethat the amount of horizontal oscillating movement of the pivot 30 ofthe forked connecting rod 29 is equal to the eccentric diameter of thetriangular cam.

The relation between the above mentioned mechanism and the verticalmovement of the needle-bar and the rotating mechanism of the shuttle I9is as follows:

Referring to Fig. 1 and Fig. 2, the rotation of the main shaft lprovides, through the needle-bar crank rod 2 and the needle-bar recess3, the up and down movement of the needle-bar 4, and further, at therear turns the vertical connecting rod I2 by means of gears l0 and I I,and transmits rotation to the horizontal shaft [5 by means of the gearsl3 and Hi. The frame of the machine, partly in section, is shown at 5.The horizontal shaft l5 and shuttle shaft l8 are in contact with eachother face to face by the semi-circular cross sections l5, 13 in theinterior of the connecting rod sleeve 18. The connecting rod sleeve 16is fastened to the horizontal shaft [5 by the push screw 11. Theoscillating rock shaft 9 is vertically borne in parallel with thevertical connecting rod l2 by pivot pins 23, slightly to one side of themain shaft I. If the arm rod fastened to the oscillating shaft isoperated horizontally, the connecting arm 6 of the needle-bar 4 is madeto oscillate by means of the connection 24, the connecting piece 8 andthe rod 1. In addition the needle-bar 4 shifts positions horizontallybetween 41, Am, 6r (left, middle and right) while making an up-and-downsewing movement by means of the needle-bar crank rod 2. At the sametime, the arm 26 fastened to the lower end of the oscillating rock shaft9 is moved left and right synchronously with the rod 1, andconsequently, the rod 22 connected at the end of the arm 25 shifts theposition of the shuttle I9, through the connecting piece 2! and sleeve29, in exactly the same amount as the horizontal movement of theneedle-bar.

The mechanism of this invention, described above, functions as follows:

As the rotating main shaft l causes the triangular cam 28 to rotate,through the 2:1 speed reduction gears 46, ll, the forked connecting rod29 is swung right and left with the shaft 30 as the center. is connectedat the pivot 30 with the arm handle 43 provided on the basic shaft 3|,it is, in principle, shifted by the shift lever 32 to the threepositions of left, middle and right, with the basic shaft 31 as thesupporting point. Thus the forked connecting rod 29 oscillates betweenthese three positions.

The slider 36 pivoted to the concentric shaft of the shaft of theconnecting rod 34 is fitted in with the arc groove 33 on the back sideof the forked connecting rod 29. The connecting piece 8 and the rod '1which cause the needle-bar 4 to shift horizontally are connected withthe connection 24 at the other end of the connecting rod 34. Theoscillating movement of the shuttle I9 is done through the oscillatingrock shaft 9 from the arm 25. A freely rotatable sleeve is movablyfitted at the upper portion of the said oscillating rock shaft 9. Tothis sleeve are fastened the zigza shifting lever 3'1 and arm plate 38and the end of it and the middle of the connecting rod 34 are connectedwith each other at the shafts 39 and 4 by the connecting piece ll.Consequently, if the zigzag shifting lever 31 is shifted to the leftside, the slider 36 is drawn toward the oscillating pivot 30 of theforked connecting rod 29. When the zigzag shifting lever 37 is at theextreme left 31 min. and the center 35 of the slider 36 agrees with theposition of the oscillating center shaft, the forked con necting rod 29,however hard it oscillates, can never cause the connecting rod 34 to beaffected. On the other hand, if the zigzag shifting lever 3! is moved tothe right, the slider 36 is drawn further away from the oscillationcenter pivot 30, and the connecting rod 34 is started, thus enlargingthe amount of the zigzag.

The above described function is illustrated in Fig. 8. Fig. 8, A showsthe position when the zigzag shifting lever 31 has been shifted to theSince the forked connecting rod 29 extreme left 31 min. and consequentlythe slider center 35 has agreed With the center of the pivot 30, thatis, with the center of rocking of the forked connecting rod 29. If theshifting lever 32 is positioned at 321*, the slider 36 and the pivot 30are positioned at 35 min. 7- 30 in the drawing, and the needle-bar 4 andshuttle l9 run straightly along the line 1 of Fig. '7, A. Likewise, ifthe shift lever 32 is shifted to 32m, the slider center 35 and the pivot30 are positioned at 35 min. m. 30m, and the end shaft 24 of theconnecting rod 34 is shifted to 24m and runs straightly on the line m inFig. 7, A. If the shift lever 32 is shifted to 321, straight runningstitches are formed on the line Z of Fig. 7, A.

Fig. 8, B is the illustration of the case when the zigzag amount isincreased or decreased by the operation of the zigzag changing lever 3'1when the position shifting lever 32 is shifted to the position of 321and the pivot 30 is at 301'. As the triangular cam 28 is rotated, theforked connecting rod 29 is oscillated, and the slider shaft 35 moves toand fro in an arc with 30m as the center, by the operation of theconnecting rod 34, the arm 25 and the connecting piece ll.

Since the amount of the horizontal shift of the pivot 30 is made equalto the eccentricity of the triangular cam 28, 241' is positioned at thecenter of the are 337' 35 max 1". When the zigzag amount is increasedwith the swinging of the forked connecting rod 29, that is, when thezigzag amount changing lever 31 is shifted to the right, the slidershaft 35 starts from the swinging center pivot 30 of the forkedconnecting rod 29, slides along on the arc groove 33, and moving betweenthe arcs 307', 35 max, 301- 35 max 1, detaches from 391'. The furtheraway it moves from 301', the greater will become the swinging width. Atthe limit, the slider center 35 moves back and forth on the are 35 max.7 and 35 max. 1. As the 241 is at the center of the are 302" 35 max r,the point 24 swings toward 241, with 261' always as the right extremity,in an arc with the oscillating rock shaft 9 as the center radius, andarrives at 241 when the slider shaft 35 is furthest away from 301'.Consequently the zigzag amount is the greatest at this point, andincreases or decreases with the amount of shift of the zigzag amountchange lever 31, thereby forming the zigzag seams, expanding toward theleft (in the direction of the line 1) with the line 1" always as theright basic line, as shown in Fig. 7, B.

In a similar way, Fig. 8, C shows the case when the zigzag amount isincreased and decreased by the zigzag amount changing lever 31, with theshifting lever 32 positioned at the center 32m. In this case the 24m isat the center of the arc 39m 35 max m. Seams which expand toward left Zand right 1" equally, with the expansion of the zigzag amount, areformed, with the line m always as the central basis line, as shown inFig. 7, C.

Fig. 8, D shows the case when the zigzag amount is increased anddecreased by the zigzag amount change lever 37, with the shifting lever32 positioned at 321. In this case, the 241 comes at the center of thearc 351 35 max 1. Consequently the zigzag seams which extend toward theright (in the direction of the line 1") with the line A always as theleft basis line, as shown in Fig. 7, D.

I claim:

1. A double-thread sewing machine having zigzag sewing mechanism,comprising a main drive shaft, speed reduction gears driven thereby, ashaft-mounted triangular cam driven by the speed reduction gears, aforked connecting rod oscillated by the triangular cam and having anarcuate groove therein, a slider guided by the arcuate groove in thetriangular cam, a needle bar and a shuttle, in combination with a rockshaft for the shuttle and needle bar adapted to move the latter twoparts laterally, an arm rod and a connecting rod connecting the sliderto the rock shaft, a sleeve on the rock shaft, an arm plate on thesleeve, a link connecting the end of the arm plate to the connectingrod, the length of the arm plate and the distance on the connecting rodfrom the arm rod to the link being equal; said forked connecting rodbeing pivotally carried from a basic shaft by an arm handle and therebeing a zigzag control lever fitted on the arm handle: the dimensions ofthe parts being such that with the shift lever in central position andthe slider in registry with the pivot of the forked connecting rod, thefollowing four lengths are equal and parallel (a) from the said pivot ofthe forked connecting rod on the arm handle to the basic shaft, (1))from the said pivot to the shaft carrying the triangular cam, (c) thelength of the connecting link, and (d) the length of the arm rod;whereby the amount of horizontal oscillating movement of the pivot ofthe forked connecting rod is equal to the eccentric diameter of thetriangular cam.

2. A double-thread sewing machine according to claim 1 in which there isa second lever connected to the rock shaft sleeve adapted tomove theslide and thereby to change the amount of zigzag.

References Cited in the file of this patent FOREIGN PATENTS NumberCountry Date 363,084 Italy Sept. 17, 19 8 694,877 Germany Aug. 9, 1940

